This proposal is part of an IRPG project whose overall goal is to define the genetic, developmental, and endocrinological bases of tumorigenesis in germ cells and in companion granulosa cells. This proposal focuses on the mechanisms of ovarian granulosa cell (GC) tumorigenesis, and like the other two projects, will exploit unique mouse models for spontaneous ovarian tumorigenesis and integrate complementary skill and resource in the areas of genetics, developmental biology, and endocrinology to promote efficiency and maximize prospects for success. Tumors of the ovarian granulosa cell compartment in humans represents a serious gynecologic disease with bimodal distribution in older women and in juveniles from birth to menarche. Consistent etiologic factors associated with these tumors include genetic factors and reproductive hormones. This project proposes to map susceptibility genes and determine the role of follicular compartments in GC tumorigenesis. The proposed investigations use a mouse model for heritable juvenile onset tumors developed in SWR, in their Fl hybrids, and in SWXJ recombinant inbred strains. These GC tumors occur spontaneously at rates up to 28%, are regulated by sex steroid hormones, express increased numbers of epidermal growth factor receptors, form during the peripubertal period, are highly malignant, and have morphologic and endocrinologic features similar to those observed for young girls. To accomplish the mapping of susceptibility genes, analyses will be undertaken of segregating genes in F2 progeny from SWR and SJL progenitor strains, in progeny from SWXJ recombinant inbred strains, and in backcross progeny from SWR crossed with SWXL-4 strain mice. DNA will be typed for PCR based simple sequence repeat markers displaying polymorphic variation distinguishing SWR, SJL, and C57L alleles. To accomplish the analyses of follicular cell compartments, culture techniques will be adopted that were specifically developed for immature whole follicles, oocyte-granulosa cell complexes, and granulosa cells without oocytes. These follicular compartments will be placed in culture under defined conditions with gonadotropin or C19 androgenic stimulation known to induce tumors in vivo. Assessment of tumorigenic initiation is based on a bioassay developed in severe combined immune deficiency (scid) and in hormone deficient (hpg/hpg scid/scid) host mice to identify their roles in initiation of GC tumorigenesis. Together these studies will generate new information about the genes, cell types, and hormonal stimuli needed to understand the mechanisms of ovarian granulosa cell neoplasia.